mk/subst.mk: add SUBST_NOOP_OK to catch typos and outdated definitions

In a bulk build with very strict settings (WARNING_MSG fails, as well as
no-op substitutions), it became clear that nearly all of the cases where
SUBST didn't replace anything were bugs in the package definition.

Most of them were just outdated, which is no surprise given that some
packages are already over 20 years old.

For backwards compatibility, SUBST_NOOP_OK defaults to "yes" right now.
After correcting the affected packages, the default will change to "no".

1 files changed, 29 insertions, 6 deletions

diff --git a/mk/subst.mk b/mk/subst.mk
index fb848898c20..452d0102297 100644
--- a/mk/subst.mk
+++ b/mk/subst.mk
@@ -1,4 +1,4 @@
-# $NetBSD: subst.mk,v 1.62 2019/11/22 18:04:49 minskim Exp $
+# $NetBSD: subst.mk,v 1.63 2020/03/19 16:57:35 rillig Exp $
 #
 # The subst framework replaces text in one or more files in the WRKSRC
 # directory. Packages can define several ``classes'' of replacements.
@@ -32,6 +32,10 @@
 #	A list of file patterns on which to run the substitution;
 #	the filenames are either absolute or relative to ${WRKSRC}.
 #
+#	Starting with 2020Q1, it is an error if any of these patterns
+#	has no effect at all, to catch typos and outdated definitions.
+#	To prevent this, see SUBST_NOOP_OK.<class> below.
+#
 # SUBST_SED.<class>
 #	List of sed(1) arguments to run on the specified files.
 #	Multiple commands can be specified using the -e option of sed.
@@ -44,7 +48,7 @@
 #		-e 's,@VARNAME@,${VARNAME},g'
 #
 #	that even works when ${VARNAME} contains arbitrary characters.
-#	Both SUBST_SED and SUBST_VARS can be used in a single class.
+#	SUBST_SED and SUBST_VARS can combined freely.
 #
 # SUBST_FILTER_CMD.<class>
 #	Filter used to perform the actual substitution on the specified
@@ -59,6 +63,13 @@
 #	During development of a package, this can be set to "yes" to see
 #	the actual changes as a unified diff.
 #
+# SUBST_NOOP_OK.<class>
+#	Whether to fail when a SUBST_FILES pattern has no effect.
+#	In most cases, "yes" is appropriate, to catch typos and outdated
+#	definitions.
+#
+#	Default: no (up to 2019Q4), yes (starting with 2020Q1)
+#
 # See also:
 #	PLIST_SUBST
 #
@@ -69,7 +80,7 @@ _VARGROUPS+=		subst
 _PKG_VARS.subst=	SUBST_CLASSES
 .for c in ${SUBST_CLASSES}
 .  for pv in SUBST_STAGE SUBST_MESSAGE SUBST_FILES SUBST_SED SUBST_VARS	\
-	SUBST_FILTER_CMD SUBST_SKIP_TEXT_CHECK
+	SUBST_FILTER_CMD SUBST_SKIP_TEXT_CHECK SUBST_NOOP_OK
 _PKG_VARS.subst+=	${pv}.${c}
 .  endfor
 .endfor
@@ -85,6 +96,10 @@ ECHO_SUBST_MSG?=	${STEP_MSG}
 _SUBST_IS_TEXT_FILE_CMD?= \
 	[ -z "`LC_ALL=C ${TR} -cd '\\0' < "$$file" | ${TR} '\\0' 'x'`" ]
 
+.if ${SUBST_CLASSES:U:O} != ${SUBST_CLASSES:U:O:u}
+PKG_FAIL_REASON+=	"[subst.mk] duplicate SUBST class: ${SUBST_CLASSES:O:u}"
+.endif
+
 .for _class_ in ${SUBST_CLASSES}
 _SUBST_COOKIE.${_class_}=	${WRKDIR}/.subst_${_class_}_done
 
@@ -99,6 +114,7 @@ _SUBST_KEEP.${_class_}?=	${DIFF} -u "$$file" "$$tmpfile" || true
 .  endif
 _SUBST_KEEP.${_class_}?=	${DO_NADA}
 SUBST_SKIP_TEXT_CHECK.${_class_}?=	no
+SUBST_NOOP_OK.${_class_}?=	yes # TODO: change to no after 2020Q1
 
 .if !empty(SUBST_SKIP_TEXT_CHECK.${_class_}:M[Yy][Ee][Ss])
 _SUBST_IS_TEXT_FILE_CMD.${_class_}=	${TRUE}
@@ -120,9 +136,10 @@ ${_SUBST_COOKIE.${_class_}}:
 .  if !empty(SUBST_MESSAGE.${_class_})
 	${RUN} ${ECHO_SUBST_MSG} ${SUBST_MESSAGE.${_class_}:Q}
 .  endif
+.for pattern in ${SUBST_FILES.${_class_}}
 	${RUN} cd ${WRKSRC:Q};						\
-	files=${SUBST_FILES.${_class_}:Q};				\
-	for file in $$files; do						\
+	changed=no;							\
+	for file in ${pattern}; do					\
 		case $$file in /*) ;; *) file="./$$file";; esac;	\
 		tmpfile="$$file.subst.sav";				\
 		if [ ! -f "$$file" ]; then				\
@@ -138,6 +155,7 @@ ${_SUBST_COOKIE.${_class_}}:
 				${INFO_MSG} "[subst.mk:${_class_}] Nothing changed in $$file."; \
 				${RM} -f "$$tmpfile";			\
 			else						\
+				changed=yes;				\
 				${_SUBST_KEEP.${_class_}};		\
 				${MV} -f "$$tmpfile" "$$file"; 		\
 				${ECHO} "$$file" >> ${.TARGET};		\
@@ -145,6 +163,11 @@ ${_SUBST_COOKIE.${_class_}}:
 		else							\
 			${WARNING_MSG} "[subst.mk:${_class_}] Ignoring non-text file \"$$file\"."; \
 		fi;							\
-	done
+	done;								\
+	\
+	if test "$$changed,${SUBST_NOOP_OK.${_class_}:tl}" = no,no; then \
+		${FAIL_MSG} "[subst.mk:${_class_}] The pattern "${pattern:Q}" has no effect."; \
+	fi
+.endfor
 	${RUN} ${TOUCH} ${TOUCH_FLAGS} ${.TARGET:Q}
 .endfor